The use of cold packs for thermal therapy is known. Cold packs may be of several general types. One type of cold pack contains an insulating material which, upon cooling in a refrigerator or freezer, gradually warm back to ambient temperature. Another type of cold pack operates via a change of phase of the components of the cold pack. Still another type of cold pack employs chemical components that are endotherm-producing on dissolution in a solvent.
Phase change materials may be converted between solid and liquid phases and utilize a latent heat of fusion to absorb, store and release heat, or cool, during such phase conversion. Accordingly, the amount of energy absorbed upon melting or released upon freezing is greater than the amount of energy absorbed or released upon increasing or decreasing the temperature of the material. Ice/water is one example of a phase change material.
Certain chemical compounds, once dissolved into a solution, result in a lowering of the temperature of the solution below ambient temperature. On dissolution, these compounds absorb heat from the surrounding environment. For example, inorganic salts or soluble organic compounds known to have a positive enthalpy of aqueous solution are used to make the reduced temperature solutions useful in cold packs.
Examples of cold packs that employ an insulating material are cold packs that contain a gel. Typically, these cold packs are cooled in a refrigerator or freezer. For cold therapy, once cooled, the cold pack is placed on the injured or sore area and thus provides the cold therapy.
Chemical cold packs that provide an insulating layer between the cold pack and the skin are also known. One such cold pack uses an outer pouch containing capillaries to allow drainage of the pack and to provide a temperature moderating effect. Another chemical cold pack uses a wetting member in contact with the chemical cold pack, thereby providing moist cold to an injury. Yet another chemical cold pack positions an absorbent/insulating layer between the chemical cold and the ambient air with the chemical cold pack placed up against the patient's skin. In this device, the surface area of the absorbent/insulating layer is smaller than the surface area of the cold pack. One prior art chemical cold pack cover provides means to attach the cold pack to a patient and to provide a water-resistant material in contact with the skin.
One disadvantage of the prior art devices is that the cold packs may not easily be regenerated in situ. Additionally, the prior art devices are not readily reusable for a single application. Another disadvantage of the prior art devices is that the insulating materials, while possessing at least some absorbency, are positioned away from the injury. A further disadvantage of the prior art devices is that the absorbency of the absorbent/insulating layer is obstructed by the larger cold pack surface area. Yet another disadvantage of the prior art devices is that they are costly to manufacture.
It would therefore be an advantage to have a cold pack that can be easily regenerated in situ. It would be a further advantage to have a cold pack that would allow the simultaneous placement of cold pack and absorbent pad on the injury site. It would be yet a further advantage to provide a low cost cold pack that can be regenerated in situ and allows the simultaneous placement of the cold pack and the absorbent pad on the injury site.